Refund Offered on Non-Refundable Ticket (After 24-Hour Window)

I booked a Main Cabin Changeable/Nonrefundable fare and went to cancel it today for eCredits because the price went down and I wanted to rebook. When I got to the cancellation confirmation page, the box said "refund to original form of payment". It seems to have processed and there were no eCredits available in my account when I re-booked my flight. Has anyone had an experience like this? I'm a little worried that this was some error and they'll claw back the refund and give me eCredits after I'm out of the 24-hour window for the new booking.

Unsure if this would be the reason, but there was a flight number change for one of my legs ~2 weeks ago and that email included information on cancelling for refund due to "schedule changes" (despite there being no actual change to my flight times).